EPDM Packaging System and Process

ABSTRACT

The present disclosure provides a packaging process and the resultant package produced from the process. The process includes introducing, into a mixing device, pellets composed of ethylene/propylene/diene polymer (EPDM). The EPDM comprises greater than 60 wt % units derived from ethylene. The pellets have a residual moisture content from 500 ppm to 2500 ppm. The process includes adding a silica-based powder to the mixing device and coating at least a portion of the pellets with the silica-based powder. The process includes sealing a bulk amount of the coated pellets in a bag made of a flexible polymeric film The process includes absorbing, with the silica-based powder, the residual moisture from the pellets, and preventing moisture condensation in the bag interior for a period from 7 days after the sealing step to 1000 days after the sealing step.

BACKGROUND

The term “ethylene-propylene-diene polymer,” (or “EPDM”) as used herein,is a saturated interpolymer chain composed of units derived fromethylene, propylene, and a diene. EPDM has a wide range of applications,such as insulation for wire and cable, hoses, and molded articles, forexample.

Semi-crystalline EPDM grades (EPDM with at least 60 wt % units derivedfrom ethylene) exhibit melt fracture during pelletization. The resultingmelt fracture creates a rough surface with crevices trapping waterduring underwater pelletization, thereby making it difficult to dry theEPDM pellets in the process. Conventional dryers are unable to dry thepellets since the drying kinetics is diffusion rate controlled. Theresidual moisture results in long and costly warehouse drying times (onthe order of weeks to months) before the EPDM pellets are sufficientlydry or can be shipped to customers for use.

Over time, the residual moisture migrates from the EPDM pellets andcondenses on to the inner wall of the storage bags, or on to the innersurface of stretch-wrap covering the pallets supporting bulk pellets.This moisture condensation creates a quality concern for customers andend-use.

Conventional anti-blocking coatings such as talc and polyethylene dust,fail to mitigage moisture condensation within the packaging. A needexists for a process and system for packaging EPDM pellets, particularlysemi-crystalline EPDM pellets, which reduce moisture condensation withinthe storage package.

SUMMARY

The present disclosure provides a process. In an embodiment, the processincludes introducing, into a mixing device, pellets composed ofethylene/propylene/diene polymer (EPDM). The EPDM comprises greater than60 wt % units derived from ethylene. The pellets have a residualmoisture content from 500 ppm to 2500 ppm. The process includes adding asilica-based powder to the mixing device and coating at least a portionof the pellets with the silica-based powder. The process includessealing a bulk amount of the coated pellets in a bag made of a flexiblepolymeric film. The process includes absorbing, with the silica-basedpowder, the residual moisture from the pellets, and preventing moisturecondensation in the bag interior for a period from 7 days after thesealing step to 1000 days after the sealing step.

The present disclosure provides a package. In an embodiment, the packageincludes

A. a sealed bag formed from a flexible polymeric film; and

B. a bulk amount of coated pellets in an interior of the sealed bag. Thepellets are composed of (i) EPDM comprising at least 60 wt % unitsderived from ethylene. The pellets have a residual moisture content from500 ppm to 2500 ppm. The coated pellets include (ii) a coating on atleast a portion of the pellets. The coating comprises a silica-basedpowder, and no moisture condensation is visible in the bag interior from7 days after the bag is sealed to 1000 days after the bag is sealed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is scanning election microscope (SEM) micrograph sectional view(longitudinal) of an EPDM pellet in accordance with an embodiment of thepresent disclosure.

FIG. 1B is a SEM micrograph cross-sectional view of an EPDM pellet inaccordance with an embodiment of the present disclosure.

FIG. 2 is a graph showing the unconfined yield strength (U.S. units) vs.moisture content for an amorphous silica powder in accordance with anembodiment of the present disclosure.

FIG. 3 is a graph showing the unconfined yield strength (SI units) vs.moisture content for an amorphous silica powder in accordance with anembodiment of the present disclosure.

DETAILED DESCRIPTION 1. Process

The present disclosure provides a process. In an embodiment, the processincludes introducing pellets of ethylene/propylene/diene polymer (EPDM)into a mixing device. The EPDM includes at least 60 wt % units derivedfrom ethylene. The pellets have a residual moisture content from 500 ppmto 2500 ppm. The process includes adding a silica-based powder to themixing device and coating at least a portion of the pellets with thesilica-based powder. The process further includes sealing a bulk amountof the coated pellets in a bag made of a flexible polymeric film andabsorbing, with the silica-based powder, the residual moisture from thepellets that are sealed within the bag. The process further includespreventing moisture condensation in the bag interior for a period fromseven days after the sealing step to 1000 days after the sealing step.

The term “ethylene/propylene/diene polymer,” or “EPDM,” as used herein,is as a polymer with a majority amount of units derived from ethylene,and also includes units derived from propylene comonomer, and unitsderived from a diene comonomer.

The EPDM includes units derived from a diene monomer. The diene can beconjugated-, non-conjugated-, straight chain-, branched chain- orcyclic-hydrocarbon diene having from 6 to 15 carbon atoms. Nonlimitingexamples of suitable diene include 1,4-hexadiene; 1,6-octadiene;1,7-octadiene; 1,9-decadiene; branched chain acyclic diene, such as5-methyl-1,4-hexadiene; 3,7-dimethyl-1,6-octadiene;3,7-dimethyl-1,7-octadiene and mixed isomers of dihydromyricene anddihydroocinene, single ring alicyclic dienes, such as1,3-cyclopentadiene; 1,4-cyclohexadiene; 1,5-cyclooctadiene and1,5-cyclododecadiene, and multi-ring alicyclic fused and bridged ringdienes, such as tetrahydroindene, methyl tetrahydroindene,dicyclopentadiene, bicyclo-(2,2,1)-hepta-2,5-diene; alkenyl, alkylidene,cycloalkenyl and cycloalkylidene norbornenes, such as5-methylene-2-norbornene (MNB); 5-propenyl-2-norbornene,5-isopropylidene-2-norbornene, 5 -(4-cyclopentenyl)-2-norbornene,5-cyclohexylidene-2-norbornene, 5-vinyl-2-norbornene, norbornadiene,1,4-hexadiene (HD), 5-ethylidene-2-norbornene (ENB),5-vinylidene-2-norbornene (VNB), 5-methylene-2-norbornene (MNB), anddicyclopentadiene (DCPD).

In an embodiment, the diene is selected from VNB and ENB.

In an embodiment, the diene is ENB.

In an embodiment, the EPDM includes:

(i) at least 60 wt %, or 65 wt %, or 70 wt %, to 75 wt %, or 80, or 85wt % units derived from ethylene;

(ii) from 15 wt %, or 20 wt % to 25 wt %, or 30 wt % units derived frompropylene; and

(iii) from 0.1 wt %, or 0.3 wt %, or 0.5 wt %, to 1.0 wt %, or 5 wt %,or 10 wt % units derived from diene. Weight percent is based on thetotal weight of the EPDM.

In an embodiment, the EPDM has a Mooney viscosity from 20, or 30, or 40,or 50, or 60, to 70, or 80, or 90, or 100, or 200, or 300.

The EPDM is made by contacting ethylene, propylene, and the diene with acatalyst, a cocatalyst, and optionally a chain transfer agent underpolymerization conditions. The term “polymerization conditions,” as usedherein are temperature, pressure, reactant concentrations, solventselection, chain transfer agent, reactant mixing/addition parameters,and/or other conditions within a polymerization reactor that promotereaction between the reagents and formation of the resultant product,namely the EPDM. Catalyst, cocatalyst and optionally chain transferagent are continuously or intermittently introduced in thepolymerization reactor containing the monomers to produce the EPDM.

In an embodiment, the catalyst used to make the present EPDM may be apolyvalent aryloxyether metal complex. A “polyvalent aryloxyether metalcomplex,” as used herein, is a metal complex having the structure (I):

wherein

R²⁰ independently each occurrence is a divalent aromatic or inertlysubstituted aromatic group containing from 5 to 20 atoms not countinghydrogen;

T³ is a divalent hydrocarbon or silane group having from 1 to 20 atomsnot counting hydrogen, or an inertly substituted derivative thereof; and

R^(D) independently each occurrence is a monovalent ligand group of from1 to 20 atoms, not counting hydrogen, or two R^(D) groups together are adivalent ligand group of from 1 to 20 atoms, not counting hydrogen.

In an embodiment, the catalyst is added to the reactor such that theEPDM contains less than 0.3 ppm zirconium or from 0.1 ppm to less than0.3 ppm zirconium.

In an embodiment, the catalyst isdimethyl[[2′,2′″-[1,2-cyclohexanediylbis(methyleneoxy-κO)]bis[3-(9H-carbazol-9-yl)-5-methyl[1,1′-biphenyl]-2-olato-κO]](2-)]-zirconium.

The cocatalyst used to make the present composition is an alumoxane.Nonlimiting examples of suitable alumoxanes include polymeric oroligomeric alumoxanes, such as methylalumoxane (MAO) as well as Lewisacid-modified alumoxanes (MMAO) such as trihydrocarbylaluminum-,halogenated tri(hydrocarbyl)aluminum-modified alumoxanes having from 1to 10 carbons in each hydrocarbyl or halogenated hydrocarbyl group.

In an embodiment, the alumoxane is introduced into the polymerizationreactor such that the EPDM contains less than 3.5 ppm aluminum. In afurther embodiment, the EPDM contains from 1.0 ppm, or 2.0 ppm, or 2.5ppm, to 3.0 ppm or less than 3.5 ppm aluminum.

The catalyst and the cocatalyst are boron-free. Accordingly, in anembodiment, the present composition is boron-free.

The EPDM is in the form of a pellet. A “pellet,” as used herein, is apolymeric structure that is cylindrical, or substantially cylindrical,in shape. The pellet has a diameter from 2 millimeters (mm) or 3 mm to 9mm or 10 mm. The pellet has a length from 2 mm, or 3 mm to 15 mm, or 20mm. The pellet has a mass from 10 grams (g), or 12 g, or 14 g to 16 g,to 18 g, to 20g.

In an embodiment, the EPDM pellet has a diameter from 3 mm to 9 mm and alength from 3 mm to 15 mm.

In another embodiment, the polymer pellet has a diameter from 3 mm to 9mm and a length from 7 mm to 20 mm (often referred to as a “rod.”)

In an embodiment, the EPDM is in the form of crumbs. A “crumb” is anirregular-shaped particle (not a geometrically regular form).

In an embodiment, the EPDM pellet is a melt fracture pellet. The term“melt fracture pellet,” as used herein, is a pellet with surfaceirregularity, the surface irregularity resulting from irregularextrusion flow conditions during pelletization. Extrusion irregularitiesmay be classified into two main types: (i) surface melt fracture and(ii) gross melt fracture. Surface melt fracture ranges in detail fromloss of specular gloss to the more severe form of “sharkskin.” Grossmelt fracture ranges in detail from regular (alternating rough andsmooth, helical, etc.) to random distortions. In an embodiment, the EPDMpellets exhibit gross melt fracture. FIGS. 1A and 1B are SEM micrographsof an EPDM pellet exhibiting gross melt fracture surface irregularity.

The EPDM pellets contain residual moisture. The term “residualmoisture,” as used herein, is the average amount of moisture retained bythe pellets after the pellets have been subjected to apost-pelletization drying procedure. A post-pelletization dryingprocedure typically utilizes a convective dryer with residence time upto 5 minutes to dry EPDM pellets during the production process. Inembodiment, the EPDM pellets have a residual moisture content from 500ppm, or 600 ppm, or 700 ppm, or 800 ppm to 1000 ppm, or 1500 ppm, or2000 ppm, or 2500 ppm.

In an embodiment, the EPDM is a semi-crystalline EPDM. A“semi-crystalline EPDM” is an EPDM with greater than 60 wt % unitsderived from ethylene. In an embodiment, the EPDM is a semi-crystallineEPDM and contains from at least 60 wt % to 85 wt % units derived fromethylene.

In an embodiment, the pellets contains one, some, or all of thefollowing properties:

(i) from 500 ppm to 2500 residual moisture;

(ii) gross melt fracture surface irregularity;

(iii) EPDM containing from 60 wt % to 85 wt % units derived fromethylene;

(iv) EPDM having a Mooney viscosity from 20-300; and

(v) EPDM containing from 0.5 wt % to 10 wt % ENB.

In an embodiment, the EPDM is an oil-extended EPDM composition. An“oil-extended EPDM,” as used herein, is an EPDM composition thatcontains an (i) EPDM and (ii) at least 25 wt % oil, based on the totalweight of the composition. The EPDM of the oil-extended EPDM compositioncan be any EPDM as disclosed above. In an embodiment, the oil-extendedEPDM composition contains at least 30 wt %, or at least 40 wt % to 70 wt%, or 60 wt %, or 50 wt % oil. The oil can be an aromatic oil, a mineraloil, a naphthenic oil, paraffinic oil, and a triglyceride-basedvegetable oil such as castor oil, a synthetic hydrocarbon oil such aspolypropylene oil, a silicone oil, or any combination thereof.

The process includes introducing the EPDM pellets in a mixing device.The mixing device mechanically imparts a motion upon the pellets, orotherwise moves the pellets. Nonlimiting examples of suitable motionsand mixing devices include simple tumbling of a jar; blending in aconical rotating vessel, ribbon blender, drum tumbler, paddle blender,agglomeration pan; use of a pneumatic conveyor under air or inert gas;moderate stirring, shaking or even a short distance of conveying in ascrew conveyor.

The present process includes adding a silica-based powder to the mixingdevice and coating at least a portion of the pellets with thesilica-based powder. The term “silica-based powder,” as used herein, isa powder containing one or more silica(s) in particulate form andoptionally one or more additional blend powders.

In an embodiment, the process includes adding the silica-based powder inan amount from 3000 ppm, or 4000 ppm, or 5000 ppm, or 6000 ppm, or 7000ppm to 8000 ppm, or 9000 ppm to 10,000 ppm. Weight percent is based onthe total weight of the EPDM pellets and the silica-based powder.

The foregoing silicas are distinct from, and exclude, siloxanes whichare organosilanes. Organosilanes, including, siloxanes, include a Si—Cbond. In contrast, the present silica (SiO₂) does not include a Si—Cbond.

In an embodiment, the silica-based powder includes an amorphous silica.The term “amorphous silica,” as used herein, is a silica compoundcomposed of silicon and oxygen that does not contain a measurable amountof crystalline silica (less than 0.01 wt % relative to quartz). andexhibits a local tetrahedral structure, but no further long range orderin highly porous particles sized from 100 nm to 100 μm. The surface ofthe particles can be further modified or remain unmodified.

Amorphous silica is divided into naturally occurring amorphous silicaand synthetic forms. Naturally occurring amorphous silica such asuncalcined diatomaceous earth usually contains certain amounts ofcrystalline silica, sometimes up to 8%.

In an embodiment, the present amorphous silica is a synthetic amorphoussilica (SAS). SAS is intentionally manufactured amorphous silica thatdoes not contain measurable levels of crystalline silica (<0.01% byweight relative to quartz). SAS is produced by the wet route(precipitated silica, silica gel) or the thermal route (pyrogenicsilica). SAS, including pyrogenic silicas, precipitated silicas andsilica gels, is white, fluffy powders or milky-white dispersions ofthese powders (usually in water). SAS is hydrophilic, but can be madehydrophobic by surface treatment.

Nonlimiting examples of suitable amorphous silica are provided in TableA below.

TABLE A Some physical properties of amorphous silica powders* MedianAggregate Surface Oil Bulk Size Area Absorption Specific DensityMaterial (μm) m²/g mL/100 g Gravity kg/m³ Hi-Sil T600 1.4 150 150 2.1 56(HST600) Flow-Gard FF 10 180 210 2.0 128 (FGFF) Flow-Gard SP 25 220 2602.0 144 (FGSP) Hi-Sil SC-72 175 150 200-350 2.0 230 (SC72) *From PPGIndustries (2000)

In an embodiment, the amorphous silica is an amorphous fumed silica. Theterm “fumed silica,” as used herein, is a non-crystalline, fine-grain,low bulk density and high surface area silica. Fumed silica primaryparticle size is 5-50 nm. Fumed silica particles are non-porous andtypically have a surface area of 50-600 m²/g and a density of 2.2 g/cm³.Fumed silica is made from flame pyrolysis of silicon tetrachloride orfrom quartz sand vaporized in a 3000° C. electric arc. The compactedvolume of precipitated silica is lower than that of fumed silica sincefumed silica consists of chain-shaped aggregates whereas precipitatedsilica consists of corpuscular, 3-dimensional aggregates.

In an embodiment, the amorphous silica is an amorphous precipitatedsilica. The term “precipitated silica,” as used herein, is the reactionproduct of acidified sodium silicate followed by precipitation underalkaline conditions. Precipitated silica is distinguishable from silicagels, quartz silica, and fumed silica. Precipitated silica is porouswhereas silica gels, quartz silica, and fumed silica are non-porous.Precipitated silica typically has a broad meso/macroporous porestructure reflected in the pore size distribution, whereas other silicasgenerally have a more narrow microporous or mesoporous structure.Precipitated silica particles have an average diameter of 5-100 nm, asurface area of 5-100 m²/g, and a density of 1.9-2.1 g/cm³. Agglomeratesize is 1-40 μm with an average pore size of greater than 30 nm.

In an embodiment, the silica-based powder is a blend of a silica and oneor more blend powders. Nonlimiting examples of suitable blend powdersinclude talc, clay, mica, calcium carbonate, and any combinationthereof.

In an embodiment, the silica-based powder is a blend of amorphous silicaand talc. The silica-based powder has an amorphous silica-to-talc ratiofrom 1.0 to 2.0:1.

In an embodiment, the silica-based powder contains from 3000 ppm to 6000ppm amorphous silica and from 6000 ppm to 3000 ppm talc.

The mixing device mixes the silica-based powder with the EPDM pellets,bringing the silica-based powder into contact with the surfaces of theEPDM pellets. The silica-based powder adheres to the outer surfaces ofthe pellets by way of Van der Waals forces, electrostatic forces andmechanical adhesion on rough pellet surface. The present processexcludes adding a binding agent to the pellets.

The process includes sealing a bulk amount of the coated pellets in abag formed from a flexible polymeric film. A “bulk amount,” as usedherein, is from 15 kg to 1500 kg of the EPDM pellets.

In an embodiment, a bulk amount from 20 kg to 25 kg of coated pellets issealed in a bag.

In an embodiment, a bulk amount from 500 kg to 1200 kg of coated pelletsis sealed in a bag and the bag (a liner) is placed in a container, suchas a cardboard box container (bag-in-a-box).

In an embodiment, a bulk amount from 100 kg to 1500 kg of coated pelletsis sealed in a bag (bulk bag).

The bag is made from a flexible polymeric film. Nonlimiting examples ofsuitable polymer for the flexible film include polyethylene, ethylvinylacetate (EVA), polypropylene (PP), and polyethylene terephthalate (PET).

The process includes absorbing, with the silica-based powder, theresidual moisture from the pellets, and preventing moisture condensationon a package inner surface for a period from 7 days after the sealingstep, to 365 days (1 year) after the sealing step, to 1000 days afterthe sealing step.

As the pellets dwell in the bag interior, the residual moisture bound inthe pellets gradually leaves the pellets. The silica-based powderabsorbs this moisture migrating from the pellets. Whatever moistureescapes initial capture by the coating condenses inside the bag and issubsequently reabsorbed by the silica-based powder within 7 days. Inthis way, the silica-based powder coating prevents the residual moisturefrom the pellets from collecting or residing on the inner surface of thebag. Bounded by no particular theory, it is believed the silica-basedpowder is able to capture and retain the residual moisture and thensubsequently release the residual moisture at delayed rate that iscompatible with the water vapor transmission rate of the polymeric filmsuch that no, or substantially no, residual moisture from the pelletscondenses (i) on the bag interior or (ii) on the bag inner surface.

The present process may comprise two or more embodiments disclosedherein.

2. Article

The disclosure provides an article. In an embodiment, the article is apackage. The package includes:

A. a sealed bag formed from a flexible polymeric film;

B. a bulk amount of coated pellets in an interior of the sealed bag. Thecoated pellets are composed of

(i) ethylene/propylene/diene polymer comprising at least 60 wt % unitsderived from ethylene, the pellets having a residual moisture contentfrom 500 ppm to 2500 ppm; and

(ii) a coating on at least a portion of the pellets, the coatingcomprising a silica-based powder. No moisture condensation is visible inthe bag interior from 7 days (168 hours) after the bag is sealed, to 365days after the bag is sealed, or to 1000 days after the bag is sealed.

In an embodiment, the pellets sealed in bag have unconfined yieldstrength less than 200 pounds per square foot after 2 months of storagein a pallet at ambient temperature of 37° C.

In an embodiment, the pellets sealed in bag have an unconfined yieldstrength from 0, or greater than 0, or 10, or 50 to less than 150, orless than 200 pounds per square foot after 2 months of storage in apallet at ambient temperature of 37° C. The pellets are considerednon-blocky if the unconfined yield strength is less than 200 pounds persquare foot after 2 months of storage at 37° C. In other words, pelletswith an unconfined yield strength less than 200 pounds per square footafter 2 months storage at ambient temperature of 37° C. are considered“free-flowing” pellets.

In an embodiment, silica-based powder is an amorphous silica.

In an embodiment, the silica-based powder is a blend of an amorphoussilica and talc.

In an embodiment, the pellets are EPDM pellets that exhibit gross meltfracture surface irregularity.

In an embodiment, the EPDM has a Mooney viscosity from 20 to 300.

In an embodiment, the EPDM has a Mooney viscosity from 20, or 50 to 115,or 200, or 300.

The present package may comprise two or more embodiments disclosedherein.

Definitions

The numerical figures and ranges here are approximate, and thus mayinclude values outside of the range unless otherwise indicated.Numerical ranges (e.g., as “X to Y”, or “X or more” or “Y or less”)include all values from and including the lower and the upper values, inincrements of one unit, provided that there is a separation of at leasttwo units between any lower value and any higher value. As an example,if a compositional, physical or other property, such as, for example,temperature, is from 100 to 1,000, then all individual values, such as100, 101, 102, etc., and sub ranges, such as 100 to 144, 155 to 170, 197to 200, etc., are expressly enumerated. For ranges containing valueswhich are less than one or containing fractional numbers greater thanone (e.g., 1.1, 1.5, etc.), one unit is considered to be 0.0001, 0.001,0.01 or 0.1, as appropriate. For ranges containing single digit numbersless than ten (e.g., 1 to 5), one unit is typically considered to be0.1. For ranges containing explicit values (e.g., 1 or 2, or 3 to 5, or6, or 7) any subrange between any two explicit values is included (e.g.,1 to 2; 2 to 6; 5 to 7; 3 to 7; 5 to 6; etc.).

The terms “blend” or “polymer blend,” as used herein, is a blend of twoor more components (or two or more polymers). Such a blend may or maynot be miscible (not phase separated at molecular level). Such a blendmay or may not be phase separated. Such a blend may or may not containone or more domain configurations, as determined from transmissionelectron spectroscopy, light scattering, x-ray scattering, and othermethods known in the art.

The term “composition,” as used herein, includes a mixture of materialswhich comprise the composition, as well as reaction products anddecomposition products formed from the materials of the composition.

The terms “comprising”, “including”, “having” and their derivatives donot exclude the presence of any additional component, or procedure. Theterm, “consisting essentially of” excludes any other component orprocedure, except those essential to operability. The term “consistingof” excludes any component, procedure not specifically stated.

The term “polymer” is a macromolecular compound prepared by polymerizingmonomers of the same or different type. “Polymer” includes homopolymers,copolymers, terpolymers, interpolymers, and so on. The term“interpolymer” means a polymer prepared by the polymerization of atleast two types of monomers or comonomers. It includes, but is notlimited to, copolymers (which usually refers to polymers prepared fromtwo different types of monomers or comonomers, terpolymers (whichusually refers to polymers prepared from three different types ofmonomers or comonomers), tetrapolymers (which usually refers to polymersprepared from four different types of monomers or comonomers), and thelike.

Test Methods

DSC Crystallinity

Differential Scanning Calorimetry (DSC) can be used to measure themelting and crystallization behavior of a polymer over a wide range oftemperature. For example, the TA Instruments Q1000 DSC, equipped with anRCS (refrigerated cooling system) and an autosampler is used to performthis analysis. During testing, a nitrogen purge gas flow of 50 ml/min isused. Each sample is melt pressed into a thin film at about 175° C.; themelted sample is then air-cooled to room temperature (about 25° C.). A3-10 mg, 6 mm diameter specimen is extracted from the cooled polymer,weighed, placed in a light aluminum pan (ca 50 mg), and crimped shut.Analysis is then performed to determine its thermal properties.

The thermal behavior of the sample is determined by ramping the sampletemperature up and down to create a heat flow versus temperatureprofile. First, the sample is rapidly heated to 180° C. and heldisothermal for 3 minutes in order to remove its thermal history. Next,the sample is cooled to −40° C. at a 10° C./minute cooling rate and heldisothermal at −40° C. for 3 minutes. The sample is then heated to 150°C. (this is the “second heat” ramp) at a 10° C./minute heating rate. Thecooling and second heating curves are recorded. The cool curve isanalyzed by setting baseline endpoints from the beginning ofcrystallization to −20° C. The heat curve is analyzed by settingbaseline endpoints from −20° C. to the end of melt. The valuesdetermined are peak melting temperature (T_(m)), peak crystallizationtemperature (T_(c)), heat of fusion (H_(f)) (in Joules per gram), andthe calculated % crystallinity for polyethylene samples using theEquation below:

% Crystallinity=((H _(f))/292 J/g)×100

The heat of fusion (H_(f)) and the peak melting temperature are reportedfrom the second heat curve. Peak crystallization temperature isdetermined from the cooling curve.

Density is measured in accordance with ASTM D 792 and is reported asgrams per cubic centimeter (g/cc).

Melt index (MI) is measured in accordance with ASTM D 1238, Condition190° C./2.16 kg (g/10 minutes).

Molecular weight distribution (“MWD”)—Polymer molecular weight ischaracterized by high temperature triple detector gel permeationchromatography (3D-GPC). The chromatographic system consists of aPolymer Laboratories (Amherst, Mass., now part of Varian, Inc,Shropshire, UK) “PL-GPC 210” high temperature chromatograph, equippedwith a concentration detector (RI), a Precision Detectors (Amherst,Mass.) 2-angle laser light scattering detector, Model 2040, and a4-capillary differential viscometer detector, Model 220, from Viscotek(Houston, Tex.). The 15° angle of the light scattering detector is usedfor calculation purposes.

Data collection is performed using VISCOTEK TriSEC software version 3,and a 4-channel VISCOTEK Data Manager DM400. The system is equipped withan on-line ERC-3415α four channel degasser system from ERC Inc (Tokyo,JP). The carousel compartment is operated at 150° C. for polyethyleneand 85° C. for EPDM, and the column compartment is operated at 150° C.The columns are four Polymer Lab Mix-A 30 cm, 20 micron columns. Thepolymer solutions are prepared in 1,2,4-trichlorobenzene (TCB). Thesamples are prepared at a concentration of 0.1 grams of polymer in 50 mlof TCB. The chromatographic solvent and the sample preparation solventcontain 200 ppm of butylated hydroxytoluene (BHT). Both solvent sourcesare nitrogen purged. EPDM samples are stirred gently at 160° C. for onehour. The injection volume is 200 and the flow rate is 1.0 ml/minute.

Calibration of the GPC column set is performed with 21 narrow molecularweight distribution polystyrene standards. The molecular weights of thestandards range from 580 to 8,400,000, and are arranged in 6 “cocktail”mixtures, with at least a decade of separation between individualmolecular weights. The polystyrene standard peak molecular weights areconverted to polyethylene molecular weights using the following equation(as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621(1968)): Mpolyethylene=A×(Mpolystyrene)^(B) (1A), where M is themolecular weight, A has a value of 0.39 and B is equal to 1.0. A fourthorder polynomial is used to fit the respective polyethylene-equivalentcalibration points.

The total plate count of the GPC column set is performed with EICOSANE(prepared at 0.04 g in 50 milliliters of TCB, and dissolved for 20minutes with gentle agitation.) The plate count and symmetry aremeasured on a 200 microliter injection according to the followingequations:

PlateCount=5.54*(RV at Peak Maximum/(Peak width at 1/2 height))̂2   (2A),

where RV is the retention volume in milliliters, and the peak width isin milliliters

Symmetry=(Rear peak width at one tenth height−RV at Peak maximum)/(RV atPeak Maximum−Front peak width at one tenth height)   (3A),

where RV is the retention volume in milliliters, and the peak width isin milliliters.

Mooney viscosity (“MV”)—Interpolymer MV (ML1+4 at 125° C.) is measuredin accordance with ASTM 1646-04, with a one minute preheat time and afour minute rotor operation time. The instrument is an AlphaTechnologies Rheometer MDR 2000. For dual reactor polymerizations inseries, the Mooney viscosity of the second reactor component isdetermined by the following equation: log ML=n(A) log ML(A)+n(B) logML(B); where ML is the Mooney viscosity of the final reactor product,ML(A) is the Mooney viscosity of the first reactor polymer, ML(B) is theMooney viscosity of the second reactor polymer, n(A) is the weightfraction of the first reactor polymer, and n(B) is the weight fractionof the second reactor polymer. Each measured Mooney viscosity ismeasured as discussed above. The weight fraction of the second reactorpolymer is determined as follows: n(B)=1−n(A), where n(A) is determinedby the known mass of first polymer transferred to the second reactor.

Unconfined Yield Strength Test

As used herein, “unconfined yield strength” is measured according to thefollowing test.

The following test is a modified test from the yield strength testdescribed in Andrew W. Jenike, “Storage and Flow of Solids”, BulletinNo. 123 of the Utah Engineering Experiments Station 1964 and theuniaxial compression test described by William's, Powder Technology, 4,1970171, pp. 328-337. The test can be carried out by first filling thepolymeric material to be tested into a split steel cylinder having adiameter of two inches and a height of four inches. The material issubjected to a consolidation pressure of 275 pounds per square foot(1345 kg/m²) for three days at a temperature of 37° C. at a controlledmoisture, that is, relative humidity. After consolidation, the resultingpolymer cylinder, comprised of individual particles, is compressedbetween two parallel plates oriented on the top and bottom of thecylinder at a rate of 2 millimeter per minute at ambient conditions. Thecompressive force required to achieve the failure, that is, fallingapart, of the cylinder comprised of individual particles corresponds tothe unconfined yield strength of the bulk material for the respectivetest conditions.

Some embodiments of the present disclosure will now be described indetail in the following Examples.

EXAMPLES

1. Materials

Pellets composed of several different types of EPDM are evaluated. Theproperties for the EPDM used in the examples are provided in Table 1below.

TABLE 1 Nordel ™ Nordel ™ Nordel ™ Nordel ™ Nordel ™ Nordel ™ 4770 P245P 4725P 4760P 4785P 3722P Composition* Ethylene 70 70 70 67 68 71Propylene 25 28.5 25 28 27 28.5 ENB 05 0.5 5 5 5 0.5 Mooney 70 45 25 6085 18 viscosity Density 0.88 0.88 0.88 0.88 0.88 0.88 (g/cc)Crystallinity 13 12 12 10 8 15 (%) Tc 34 34 36 35 29 46 (° C.)*Composition - amounts are shown in wt % based on total weight EPDM.

Materials used for the coating are provided in Table 2 below.

TABLE 2 Dust Coating Type Source Key Properties Amorphous FloGard ™ FFfrom PPG Particle size distribution: Silica 3-200 microns Surface area =180 m²/g Bulk density = 128 kg/m³ Talc MP 10-52 from Specialty Particlesize distribution: Minerals 2-10 microns Bulk density = 103 kg/m³ PEDust Coathylene HA2454 Particle size distribution: from DuPont 9-200microns Bulk density = 300-500 kg/m³

Example 1

EPDM pellets (NORDEL™ 4770P) with a residual moisture of 2200 ppm arecoated in a batch drum mixer with (i) amorphous hydrophilic silica(Flo-Gard™ FF), and (ii) amorphous hydrophilic silica/talc mixture(ratio of 5:3). The comparative sample of PE dust coated pellet isobtained from the process. All samples are coated with 8000 ppm ofcoating agent. The pellet temperature during coating is approximately22° C.

The coated samples are sealed in transparent flexible polyethylene bagsand placed on a pallet in a warehouse at ambient conditions. Visualobservations for condensation inside the bag are made after 8 hours, 24hours, 48 hours, 72 hours and 168 hours.

TABLE 3 Time Elapsed, PE Dust Coating Silica Coating Silica 5000 ppm +hours (8000 ppm) (8000 ppm) Talc 3000 ppm 8 Extremely Wet Very Wet VeryWet 24 Extremely Wet Very Wet Very Wet 48 Extremely Wet Wet Wet 72Extremely Wet Almost Dry Almost Dry 168 Wet Dry Dry Definition of VisualObservations: Extremely Wet - Internal surface of the bag is saturatedwith condensed moisture appearing as large droplets. Very Wet - Veryfine droplets and condensation at all surfaces Wet - Very fine droplets,patchy and not covering all surfaces Almost Dry - Condensation is barelyvisible within the bag Dry - No visible condensation anywhere within thebag

This example as and shown in Table 3 demonstrates the noticeablereduction in free moisture on the inside surface of the sealed bags dueto the presence of amorphous hydrophilic silica (Flo-Gard™ FF) in thepellet coating. The present silica-based coating prevents moisture fromcondensing in the bag interior from 7 days (168 hours) after the bag issealed to 365 days (1 year) after the bag is sealed, to 1000 days afterthe bag is sealed.

Example 2

Various grades of NORDEL™ IP pellets are coated uniformly with PE dustat 8000 ppm and Silica at 6000 ppm (as shown in Table 4 below). Theblocking test procedure is performed on the samples after consolidationat 37° C. for 2 months at consolidation stress of 275 lb/ft² (1345kg/m²). The improved blocking characteristic of silica coated pellets isdemonstrated by the lower value of unconfined yield strength.

TABLE 4 Unconfined Yield Unconfined Yield Strength for Strength forSilica PE Dust (Coathylene HA2454) (Flo-Gard ™ FF) @ @ 8000 ppm CoatedPellets, 6000 ppm Coated Product* lb/ft² Pellets, lb/ft² 4770P 185 0 245P 242 35 4725P 195 37 4760P 251 106 4785P 295 108 3722P 157 40*Product is NORDEL ™ EPDM

TABLE 4 (With US units - pounds per square foot (lb/ft²) and SI Units -Newtons per square meter (N/m²) Unconfined Yield Unconfined YieldUnconfined Yield Strength for PE Dust Strength for PE Dust Strength forSilica (Flo- Unconfined Yield Strength (Coathylene HA2454) @ (CoathyleneHA2454) @ Gard ™ FF) @ 6000 for Silica (Flo-Gard ™ FF) @ 8000 ppm Coated8000 ppm Coated ppm Coated Pellets, 6000 ppm Coated Pellets, Product*Pellets, lb/ft² Pellets, N/m² lb/ft² N/m² 4770P 185 8854 0 0  245P 24211582 35 1675 4725P 195 9333 37 1771 4760P 251 12013 106 5073 4785P 29514119 108 5169 3722P 157 7514 40 1914

Example 3

Three 20 kg samples of EPDM (NORDEL™ 4785P) pellets are coated with 6000ppm of amorphous hydrophilic silica (Flo-Gard™ FF), 6000 ppm talc(Specialty Minerals MP 10-52) and a 50/50 mixture of silica/talc(3000/3000) at 6000 ppm respectively. The pellet moisture is measured at3700 ppm. The coated pellets are sealed in transparent flexiblepolyethylene bags and placed in an oven at 37° C. for 24 hours.Thereafter, the bags are kept at 21° C. for further visual observations(8 hr, 24 hr and 48 hr). The visual observations on condensation withinthe bag after 48 hours demonstrate improved performance of silica-basedcoatings composed of amorphous hydrophilic silica.

TABLE 5 Time Silica 3000 Elapsed, Talc Coating Silica Coating ppm + Talchours (6000 ppm) (6000 ppm) 3000 ppm 8 Very Wet Very Wet Very Wet 24Very Wet Wet Wet 48 Very Wet Almost Dry Almost Dry

Amorphous silica (hereafter “a-silica”) and a-silica/talc mixturesprevent moisture condensation on the sealed bag interior beginning fromseven days (168 hours) after sealing of the bag to 365 days (1 year)after sealing of the bag up to 1000 days after sealing the bag (1000days being the shelf-life of the EPDM pellets). Talc alone forms a moistpaste which adheres to the bag interior resulting in EPDM pellet productwith poor and undesirable appearance. The a-silica absorbs moisture dueto its porosity and favorable surface chemistry. EPDM pellets coatedwith (i) 5000-10,000 ppm a-silica or (ii) 5000-10,000 ppm ofa-silica/talc prevent residual moisture from the pellets from condensingon the inner surface of the sealed bag.

The a-silica is not conducive to dust explosion, is hydrophilic, isporous (moisture scavenging), exhibits good anti-blockingcharacteristics, is easy to apply, is food-contact acceptable, has nostatic charges, and has no adverse effect on EPDM performance orprocessing.

It has been found that the equilibrium moisture of the coating mustexceed the total residual moisture in the pellets. The equilibriummoisture at storage temperature and 100% relative humidity was measuredas follows:

Silica dust becomes cohesive as it gains moisture. Therefore, the upperlimit of moisture is determined by increase in unconfined yield strength(see FIG. 2). For FloGard FF, the upper limit on moisture absorption isfound to be approximately 2 times the weight of the powder. The graph inFIG. 2 shows the unconfined yield strength (UYS) of the FloGard FF withdifferent loading levels of water from 0 to 2.5 times the mass of theamorphous silica. From 0 to 2 times water loading the UYS isconsistently below 40 lb/ft². After 2 times water loading an increase ofthe UYS is seen to be several times higher than other samples. Thisshows that the silica begins to become cohesive when an excess loadingof water occurs.

FIG. 2 shows the FloGard FF can hold up to 2 times its weight in waterwhile still appearing dry and flowing. This level of moisture uptakeoccurs more rapidly when the FloGard FF is in direct contact with liquidwater.

It is specifically intended that the present disclosure not be limitedto the embodiments and illustrations contained herein, but includemodified forms of those embodiments including portions of theembodiments and combinations of elements of different embodiments ascome within the scope of the following claims.

What is claimed is:
 1. A process comprising: introducing, into a mixing device, pellets composed of ethylene/propylene/diene polymer comprising greater than 60 wt % units derived from ethylene, the pellets having a residual moisture content from 500 ppm to 2500 ppm; adding a silica-based powder to the mixing device; coating at least a portion of the pellets with the silica-based powder; sealing a bulk amount of the coated pellets in a bag made of a flexible polymeric film; absorbing, with the silica-based powder, the residual moisture from the pellets; and preventing moisture condensation in the bag interior for a period from 7 days after the sealing step to 1000 days after the sealing step.
 2. A package comprising: A. a sealed bag formed from a flexible polymeric film; B. a bulk amount of coated pellets in an interior of the sealed bag, the pellets composed of (i) ethylene/propylene/diene polymer comprising at least 60 wt % units derived from ethylene, the pellets having a residual moisture content from 500 ppm to 2500 ppm; (ii) a coating on at least a portion of the pellets, the coating comprising a silica-based powder; and no moisture condensation is visible in the bag interior from 7 days after the bag is sealed to 1000 days after the bag is sealed.
 3. The package of claim 2 wherein the pellets have a maximum unconfined yield strength of less than 200 pounds per square foot after 2 months storage at 37° C.
 4. The package of claim 2 wherein the silica-based powder comprises an amorphous silica.
 5. The package of claim 2 wherein the silica-based powder comprises a blend of an amorphous silica and talc.
 6. The package of claim 2 wherein the pellets comprise gross melt fracture pellets.
 7. The package of claim 2 wherein the ethylene/propylene/diene polymer has a Mooney viscosity from 20 to
 300. 8. The package of claim 2 comprising 3000 ppm to 10000 ppm of the silica-based powder. 